Quantitative determination of sulfonamide in meat by liquid chromatography–electrospray-mass spectrometry

This paper describes a newly developed liquid chromatography–electrospray-mass spectrometry (LC–ES-MS) method for the quantitative determination of nine commonly used sulfonamides (sulfadiazine, sulfapyridine, sulfamerazine, sulfamethazine, sulfamonomethoxine, sulfisoxazole, sulfadimethoxine, sulfaquinoaline and sulfaphenazole) in meat. [M+H]+ and [M+Na]+ were the two major ions detected in positive ion mode. Selective ion monitoring was employed for quantitative determination. Satisfactory linearity, 0.1–10 μg ml−1, of each compound was obtained. Blank meat samples were fortified at levels between 50 and 500 μg kg−1. [Phenyl-13C6]sulfamethazine was used as internal standard. Sulfonamides were isolated from meat with a solvent extraction procedure and then determined by LC–ES-MS. The limits of detection were below 10 μg kg−1. The application of this newly developed method was demonstrated by analyzing various beef, pork and chicken samples from local markets.